| With the development of wireless power transmission technology and the expansion of application fields,people put forward higher requirements for the efficiency of power transmission and electromagnetic impact of the system.In order to improve the performance and shielding effect of wireless power transmission system and make up for the shortage of single shielding material,this paper takes inductively coupled power transmission system(ICPT)as an example to study the application of composite magnetic material structure in wireless power transmission system.Firstly,the classification of wireless power transmission system,ICPT system,electromagnetic shielding,electromagnetic shielding materials and so on are analyzed.The modeling methods of ICPT system are compared,and the equivalent model of mutual inductance is used to model the ICPT system compensated by PS.The expressions of output power and transmission efficiency of the system are derived.The necessity of electromagnetic shielding for ICPT system is explained from two aspects of theoretical analysis and equivalent model calculation,which lays a foundation for later research.Secondly,taking a practical system as the research object,a three-dimensional magnetic field-circuit coupling simulation model based on finite element method is established,detailed description of modeling ideas,modeling steps and simulation process is given.In order to verify the accuracy of the model,the model is used to simulate the operation of the system without shielding.,the simulation and experimental inductance parameters and the current flowing through the transmitting coil and receiving coil are basically the same,which verifies the correctness of the modelFinally,the shielding structure of multi-layer composite magnets is studied by using the model.According to the characteristics of ICPT system,the common ferrite is selected as shielding material to simulate and analyze the single layer ferrite shielding.By comparing the magnetic induction intensity,shielding efficiency and mutual inductance between transmitting coil and receiving coils and other electrical quantities at some locations,it is found that ferrite shielding can increase the magnetic field in the working area and the mutual inductance between transmitting coil and receiving coils,but the shielding efficiency is relatively general.In view of the insufficient shielding effectiveness of ferrite,the characteristics of aluminum shielding are simulated and analyzed.It is found that the performance of ferrite and aluminum shielding materials complement each other.,and the double layer shielding structure of ferrite and aluminium plate is optimized.Although this structure retains the advantages of ferrite and aluminium plate,there are still some shortcomings,such as larger edge effect and lower coupling coefficient.For this reason,the double shielding is further optimized.Considering the excellent magnetic parameters of Nanocrystalline,a three layer shielding structure composed of ferrite,Nanocrystalline and aluminium foil is finally formed by adding Nanocrystalline.This structure has good shielding effect and low shielding edge effect.At the same time,it makes the mutual inductance and coupling coefficient between the transmitting and receiving coils larger,which is conducive to the transmission of wireless energy in the system.In the research process,some simulation results are compared by using the simulation test platform,and the correctness of the analysis is illustrated.The composite magnetic shielding structure based on common shielding materials is constructed,which ensures the shielding effect and improves the performance of the system.At the same time,the weight and cost of the shielding body are reduced to a certain extent,and satisfactory results are achieved,the correctness of this shielding structure is proved.It has certain reference significance and application value for shielding design of actual wireless power transmission system. |
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